The present invention relates to lubricant compositions, and to their use, for example, to coat beverage containers or conveyor systems for beverage containers. the invention also relates to beverage containers and conveyor systems treated with such lubricant compositions.
In the commercial distribution of most beverages, the beverages are packaged in containers of varying sizes made of a variety of materials. In most packaging operations, the containers are moved along conveying systems, usually in an upright position with the opening of the container facing vertically up or down, and moved from station to station, where various operations, such as filling, capping, labeling, sealing, and the like, are performed.
Lubricants are often used on conveying systems in the beverage industry during the filling of containers with beverages. There are a number of different attributes that are desirable for such lubricants. For example, the lubricant should provide an acceptable level of lubricity for the system. For containers made from plastics such as polyethylene terephlthalate (PET), the lubricant should not cause environmental stress cracking (crazing and cracking that occurs when the plastic polymer is under tension). It is also desirable that the lubricant have a viscosity which allows it to be applied by conventional pumping or application apparatus, such as sprayers, roll coaters, wet bed coaters, and the like, commonly used in the industry.
It is also important that the lubricant be compatible with the beverage so that the lubricant does not form solid deposits when it accidentally contacts spilled beverages on the conveyor system. This is important since the formation of deposits on the conveyor system may change the lubricity of the system and could require shutdown of the equipment to facilitate cleaning. Unfortunately, many currently-used lubricants contain ingredients that react with, for example, carbonated beverages to form such deposits.
The present invention provides, in one aspect, a beverage container or a conveyor for a beverage container, whose surface is coated at least in part with a coating that has been thermally cured at less than 200xc2x0 C. or radiation-cured, whereby the cured coating forms a lubricant layer on the surface of the container or the conveyor.
The invention also provides a method for lubricating a beverage container, comprising applying to at least a portion of a surface of the beverage container a thermal or radiation curable coating, and thermally curing the coating at less than 200xc2x0 C. or radiation curing the coating to provide a lubricant layer on the surface of the container.
The invention also provides a method for lubricating a conveyor system used to transport beverage containers, comprising applying a thermal or radiation curable coating to at least part of the conveying surface of a conveyor and then thermally curing the coating at less than 200xc2x0 C. or radiation curing the coating to provide a lubricant layer on the conveying surface.
In addition, the invention provides a conveyor used to transport beverage containers, which is coated on portions that contact the container with a coating that has been thermally cured at less than 200xc2x0 C. or radiation-cured, whereby the coating forms a lubricant layer on the conveyor.
The invention also provides thermal or radiation curable container or conveyor lubricating compositions comprising a film former that can be thermally cured at less than 200xc2x0 C. or radiation-cured, a thermal initiator or photoinitiator, and at least 3 weight percent of lubricating fluoropolymer particles.
The compositions used in the invention can be applied in relatively low amounts and do not require in-line dilution with significant amounts of water. The compositions of the invention provide thin, dry lubricating films. In contrast to dilute aqueous lubricants, the lubricants of the invention provide dry lubrication of the conveyors and containers, a cleaner and drier conveyor line and working area, and reduced lubricant usage, thereby reducing waste, cleanup and disposal problems. Further features and advantages of the invention will become apparent from the detailed description that follows.